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Published on: June 16, 2020
Parental origin and genome evolution in the allopolyploid Iris versicolor
K Yoong Lim1, Roman Matyasek, Ales Kovarik
1School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, UK. y.k.lim@qmul.ac.uk
This study confirms Iris versicolor is an allopolyploid, inheriting chromosomes from I. virginica and I. setosa. rDNA analysis reveals targeted loss of I. setosa loci, suggesting genome diploidization in this allopolyploid iris.
Area of Science:
- Plant evolutionary biology
- Cytogenetics
- Molecular genetics
Background:
- Iris versicolor ('Blue Flag') is a classic example of an allopolyploid species.
- Its origin has been historically studied by Anderson and Stebbins.
- This research revisits the allopolyploid origin hypothesis using modern techniques.
Purpose of the Study:
- To investigate the allopolyploid origin of Iris versicolor.
- To identify the specific progenitor species involved: I. virginica and I. setosa.
- To analyze the inheritance and location of ribosomal DNA (rDNA) loci.
Main Methods:
- Genomic in situ hybridization (GISH) to determine chromosome origins.
- Fluorescent in situ hybridization (FISH) for rDNA locus identification.
- Southern hybridization to analyze rDNA unit structure and abundance.
Main Results:
- GISH confirmed I. versicolor inherited chromosomes from both I. virginica and I. setosa.
- All 18-26S ribosomal DNA (rDNA) loci in I. versicolor originate from the I. virginica progenitor.
- 5S rDNA loci from both progenitors were present, with one locus from the I. setosa progenitor missing.
Conclusions:
- The findings support the hypothesis of an allopolyploid origin for I. versicolor from I. virginica and I. setosa progenitors.
- The number of 18-26S rDNA loci in I. versicolor resembles I. virginica, indicating early genome diploidization.
- Targeted loss of I. setosa-derived rDNA loci suggests a mechanism in polyploid genome evolution.
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